U.S. Published Application 2005/0020926 discloses a scanning beam imager (SBI) which is reproduced in FIG. 1 herein. This imager can be used in applications in which cameras have been used in the past. In particular it can be used in medical devices such as video endoscopes, laparoscopes, etc.
FIG. 1 shows a block diagram of one example of a scanned beam imager 102. An illuminator 104, which is part of a variable illuminator 109, creates a first beam of light 106. A scanner 108 deflects the first beam of light across a field-of-view (FOV) 111 to produce a second scanned beam of light 110, shown in two positions 110a and 110b. The scanned beam of light 110 sequentially illuminates spots 112 in the FOV 111, shown as positions 112a and 112b, corresponding to beam positions 110a and 110b, respectively. While the beam 110 illuminates the spots 112, the illuminating light beam 110 is reflected, absorbed, scattered, refracted, or otherwise affected by the object or material in the FOV 111 to produce scattered light energy. A portion of the scattered light energy 114, shown emanating from spot positions 112a and 112b as scattered energy rays 114a and 114b, respectively, travels to one or more detectors 116 that receive the light and produce electrical signals corresponding to the amount of light energy received. Image information is provided as an array of data, where each location in the array corresponds to a position in the scan pattern. The electrical signals drive a controller 118 that builds up a digital image and transmits it for further processing, decoding, archiving, printing, display, or other treatment or use via interface 120.
Illuminator 104 may include multiple emitters such as, for instance, light emitting diodes (LEDs), lasers, thermal sources, arc sources, fluorescent sources, gas discharge sources, or other types of illuminators. In some embodiments, illuminator 104 comprises a red laser diode having a wavelength of approximately 635 to 670 nanometers (nm). In another embodiment, illuminator 104 comprises three lasers: a red diode laser, a green diode-pumped solid state (DPSS) laser, and a blue DPSS laser at approximately 635 nm, 532 nm, and 473 nm, respectively. Light source 104 may include, in the case of multiple emitters, beam combining optics to combine some or all of the emitters into a single beam. Light source 104 may also include beam-shaping optics such as one or more collimating lenses and/or apertures. Additionally, while the wavelengths described in the previous embodiments have been in the optically visible range, other wavelengths may be within the scope of the invention. Light beam 106, while illustrated as a single beam, may comprise a plurality of beams converging on a single scanner 108 or onto separate scanners 108.
One example of these scanners employs a MEMS scanner capable of deflection about two orthogonal scan axes, in which both scan axes are driven at a frequency near their natural mechanical resonant frequency of the MEMS device upon which it is constructed. In another example, one axis is operated near resonance while the other is operated substantially off resonance. For completeness it is also noted that scanners are also know that employ two reflectors, one of which oscillates sinusoidally and the other of which simply scans linearly.
Scanning beam imagers are advantageous because they are often able to provide higher resolution and a broader scan area. The SBI is able to provide pixel by pixel interrogation with a high range of data capture. However, even with a SBI there are some the anatomy structures within the anatomy that are difficult to examine, like the biliary tree, colon, and the gastrointestinal tract. The SBI can be adapted, as in the present invention, for use in fluorescent imaging to visualize the anatomy or an instrument that is fluorescing due to the presence of a fluorescent probe or fluorophore. Provided herein is a system that is an improvement in fluorescent imaging of the anatomy; a system that is capable of visualizing the biliary tree during a cholecystectomy or cancer cells during a colorectal cancer resection or lumpectomy, or ureters during a colorectal or gynecological procedure.